Mobile telephones have traditionally been voice-centric devices with proprietary operating systems handling all communication tasks. The Application Programming Interfaces (APIs) in these devices were not made available to third-party developers. As a consequence, end users were dependent on the device manufacturers for applications.
Today, the mobile communications industry is increasingly becoming aware of the importance and benefits of open application environments for mobile devices. Basically, an open application environment permits the installation of third party applications on the mobile device during device manufacture or later on by a user operating the device. Such third party applications may include games, software upgrades, etc.
A. Ghosh et al., “Open application environments in mobile devices: Focus on JME and Ericsson Mobile Platforms”, Ericsson Review No. 2, Vol. 82, 2005, pages 82 to 91 (ISSN: 0014-0171) describe an exemplary open application environment for mobile devices. The open application environment is based on a mobile platform with a digital baseband processor supporting one or more RATs such as General Packet Radio Service (GPRS), Enhanced Data for GSM Evolution (EDGE) or Wideband Code-Division Multiple Access (WCDMA). The mobile platform is an environment that includes all the necessary integrated circuits and software needed to provide wireless network access services and communication services (e.g. for voice, data or multimedia applications), as well as interfaces to make these services available to applications residing within or on top of the mobile platform.
As wireless access points supporting different kinds of RATs are becoming ubiquitous, it is only a logical consequence that many mobile platform chips provide support for more than one RAT. However, from the perspective of modularity it is sometimes desirable to co-locate in one mobile device two or more platform chips each supporting a different RAT. Such a modular approach facilitates re-using a mobile platform either in a stand-alone configuration or in any combination with other mobile platforms.
WO-A-00/22857 teaches a modular approach in which different network access modules (such as a Local Area Network (LAN) module and a Global System for Mobile communications (GSM) module) are interconnected via a communication bus according to the Universal Serial Bus (USB) standard. Other modules connected to the communication bus such as a Closed-Circuit Television (CCTV) module may then selectively transmit signals via the LAN module on the one hand or via the GSM module on the other.
Mobile platforms are often incorporated in modem devices like network cards that provide wireless network access to terminal devices such as PCs or laptops. Such modem devices often support two or more different RATs to ensure the availability of network access in various environments. Due to modularity considerations, two or more different mobile platforms may therefore concurrently be installed within a modem device.